1. Field of the Invention
The present disclosure relates to the field of refrigerants for use in air conditioning or refrigeration equipment. In particular, the present disclosure relates to refrigerants for use in chillers (especially centrifugal chillers) and compositions used therein.
2. Description of Related Art
Working fluids for various applications are being sought that have lower environmental impact than currently used working fluids. The hydrochlorofluorocarbon (HCFC) and hydrofluorocarbon (HFC) working fluids adopted as replacements for chlorofluorocarbon (CFC) working fluids, have lower or no ozone depletion potential (ODP), but have raised concerns as to their contribution to global warming. Additionally, the HCFCs will finally reach the phase out deadline set by the Montreal Protocol due to ODP. With regulations coming in force soon based on global warming potential, even the HFCs, with zero ODP will not be environmentally acceptable working fluids.
Therefore, replacements are sought for the CFCs, HCFCs, and HFCs currently in use as refrigerants, heat transfer fluids, cleaning solvents, aerosol propellants, foam blowing agents and fire extinguishing or suppression agents.
In order to serve as drop-in replacements of working fluids in existing equipment, replacement working fluids must have properties that closely match the properties of the original working fluids for which the equipment was designed. It would be desirable to identify compositions that provide a balance of properties that will allow replacement of existing refrigerants and also to serve as refrigerants in new equipment designed for similar applications.
In searching for a replacement for 1,1,1,2-tetrafluoroethane (HFC-134a) and difluorotrichloromethane (CFC-12) in particular in chiller applications, it would be desirable to consider compositions comprising unsaturated fluorocarbons. The unsaturated fluorocarbons have zero ODP and significantly lower GWP than the refrigerants in use today.